Final answer:
The constant in the expression (5n - 2m/7 + 3/4) is (3/4), making the correct answer c) (3/4).
Step-by-step explanation:
In the given expression (5n - 2m/7 + 3/4), a constant is a value that does not change and does not contain any variables. In this expression, n and m are variables, thus any term with n or m is not a constant.
The only term that does not contain a variable is (3/4), so this is the constant in the expression.
The answer to the question is c) (3/4).