Step 1: Check the truth of Assertion (A) alone, low agricultural marketing efficiency is a recognized fact, so (A) is true.
Step 2: Check the truth of Reason (R) alone, too many intermediaries in agri marketing is also a documented fact, so (R) is true.
Step 3: More intermediaries directly raise costs and lower farmer returns, so (R) explains (A).
\[ \boxed{\text{Both (A) and (R) true, (R) explains (A), Option (1)}} \]