heat engine absorbs heat from a source at $1000$ K at a rate of $250$ KW and rejects $100$ kW of it to a sink at $300$ K$.$ The maximum possible thermal efficiency this heat engine can have is

$($a$)0\mathrm{.}40-($b$)0\mathrm{.}50$

C$19$W

$($c$)0\mathrm{.}60$

$($d$)0\mathrm{.}70$

$($e$)1$