Strangely enough, two of those things are not like the others, but apparently it only marked one of them as wrong.
All of the options above are arguably hash functions, in that they all take some input message and produce a "digest" or "hash": a fixed-length set of high-entropy bits that is deterministic on its inputs but is not reversible. There are differences in both inputs and usage between them, though.
MD5, RIPEMD, and SHA (now usually called SHA1) are all very much the same class of function, taking just one input (an arbitrary message) and quickly producing the digest of that message (which, at least in theory, possesses collision and pre-image resistance). Their particular characteristics (both mechanically, such as length of digest, and practically, such as security) vary, but at a high level they are interchangeable.
Bcrypt takes two additional parameters: a salt, and a cost/work factor. Additionally, it is intended for hashing only short strings (passwords or similar), and constrains the input length to 72 useful bytes. It produces output like a standard hash function, but (possibly much) more slowly.
HMAC is a construction that requires an externally-defined hash function. As a function, HMAC requires inputs of a message, a salt, and a hash function to use. Unlike bcrypt, it does not introduce any constraints on the input message - in this way, it is more like the other three - but unlike all four of the others it does not actually specify an algorithm for computing a digest, delegating that operation to the specified hash function.
In summary, you could make a case for any of the following answers:
- All five are hash functions, because they take a message and produce a one-way, fixed-length, deterministic, high-entropy digest.
- Bcrypt is the only one that's not a hash function, because it cannot operate on arbitrary-length messages.
- HMAC is the only one that's not a hash function, because it doesn't define a procedure for computing a digest.
- Only MD5, RIPEMD, and SHA are true hash functions.
Evidently, your study material takes the second view. I personally lean more toward the third or fourth view. HMAC-SHA-256 is a hash function (that differs from the "pure" ones by requiring a key), but HMAC by itself isn't a hash function. It would be like saying "obtain flour, salt, water, and a person who knows how to make tortillas; give the flour, water, and salt to the person; tell the person to produce a tortilla" is a tortilla recipe.