To convert the number \( 241_5 \) from base 5 to base 8, we'll follow these steps:

1. Convert \( 241_5 \) to base 10 (decimal):
\[
241_5 = 2 \times 5^2 + 4 \times 5^1 + 1 \times 5^0
\]
\[
= 2 \times 25 + 4 \times 5 + 1 \times 1
\]
\[
= 50 + 20 + 1 = 71
\]

So, \( 241_5 = 71_{10} \).

2. Convert \( 71_{10} \) to base 8:
Divide 71 by 8 and keep track of the remainders:
\[
71 \div 8 = 8 \text{ remainder } 7
\]
\[
8 \div 8 = 1 \text{ remainder } 0
\]
\[
1 \div 8 = 0 \text{ remainder } 1
\]

So, \( 71_{10} = 107_8 \).

Therefore, \( 241_5 \) in base 8 is B. 107₈.