After more than four decades of research and development, a new type of jet engine is
being tested that could eventually propel aircraft anywhere in the world within two hours
or help boost cargoes into space at significantly lower costs than current methods permit.
A. tested that could eventually propel aircraft anywhere in the world within two
hours or help
B. tested that could eventually have the capability of propelling aircraft anywhere in
the world within two hours or to help
C. tested, eventually able to propel aircraft anywhere in the world within two hours,
or helping

D. tested, and it eventually could propel aircraft anywhere in the world within two
hours or helping
E. tested, and it could eventually have the capability to propel aircraft anywhere in
the world within two hours or help

pls explain