Упростите выражение \(\frac{21m}{25+10m+m^2}\cdot \frac{5+m}{7m^4}\) .

• \(\frac{3}{m^3(5+m)}\)
• \(3m(5+m)\)
• \(\frac{147m^9}{(5+m)^3}\)
• \(\frac{3m}{15+m^2}\)