Let the total number of matches be \( x \). According to the problem, two-thirds of the total matches are considered, i.e., \( \frac{2}{3}x \) matches. The team has won 17 matches and lost 3, so it has played $17 + 3 = 20$ matches.
Let the maximum number of matches the team can lose be \( L \). Thus, the total number of matches won will be \( 17 \), and the total matches played will be \( 20 + L \). The team wins more than three-fourths of the total matches, so:
\[
\frac{17}{20 + L}>\frac{3}{4}
\]
Step 1: Solve the inequality:
\[
\frac{17}{20 + L}>\frac{3}{4} \Rightarrow 4 \times 17>3 \times (20 + L) \Rightarrow 68>60 + 3L
\]
Step 2: Simplify the inequality:
\[
68 - 60>3L \Rightarrow 8>3L \Rightarrow L<\frac{8}{3} \approx 2.67
\]
Thus, the team can lose at most 2 matches to maintain the winning ratio above 3/4. Therefore, the correct answer is 8.