Alright, let’s think this through together. When a particle moves close to the speed of light, its mass increases due to relativity — that factor comes from \( m = \frac{m_0}{\sqrt{1 - v^2/c^2}} \). If we plug in \( v = 0.8c \), we can work out that multiplier and see which option matches.  

Do you wanna try calculating it together and see which one pops out?